1. Field of the Invention
The present invention relates to a microstrip line feeding slot type planar antenna, more particularly, to a leaky-wave dual polarized slot type antenna, capable of transmitting and receiving orthogonal polarized waves.
2. Description of the Related Art
Radars used in ultra high frequency bands and microwave bands, base station antennas, and antennas for use in satellite communications and satellite broadcasts should have high gains. To have high gains, antennas must have directivity, for example, parabolic antennas.
However, since a parabolic antenna occupies a large surface area for high gain, communication equipment of a base station should be substantially large. Also, the surface of the antenna is usually coated with endocrine disrupter containing materials to prevent rust. As a result, the parabolic antenna causes environment pollution not only when it is used but also when it is disposed.
As an attempt to solve the above problems, radio connection methods for reducing the size and weight of communication equipment of a base station, and development of power controllers and interference controllers, terminals, and network system techniques are making active progress. In particular, a planar antenna such as a microstrip line antenna is small, light and thin, so it is very convenient to use and cheap to manufacture.
The planar antenna, e.g. microstrip line antenna, is utilized for military communications where mobility and maneuverability are required. High communication equipment such as next generation mobile communication system also uses planar antennas for the same reasons.
However, the microstrip line antenna being currently commercialized has drawbacks in that its frequency bandwidth is very narrow and has a low gain. Moreover, it can transmit/receive a single polarized wave only. Thus, to transmit/receive dual polarized waves, a vertically polarized antenna and a horizontally polarized antenna had to be used together at the same time.